Directeur scientifique de l'INRS,avenue de Bourgogne, 54500 Vandoeuvre.
Everyone and everything is called upon to account for themselves, to be evaluated... people, organized social systems, and, more generally, states. The French word "expertise" is a protean term that can validate (almost)everything: like Harlequin's particolored costume, it has several dimensions and is based on several concepts. It relies upon the elitist and humanist values, even criteria, of transparency and independence (or not)... But complexity attacks "expertise" today inside its fortifications. This short essay is not intended to provide ready-made solutions in a domain that is both difficult and sensitive. The authors nonetheless hope that it will provide a basis for reflection on this important subject and lead finally to the development of public confidence.